1. Field of the Invention
The present invention relates to a negative pressure gauge, and in particular to a negative pressure gauge with a switch.
2. Description of Prior Art
A common negative pressure gauge has to be provided with a display unit for displaying the amount of airflow in operation, so that a user can adjust the amount of gas flowing through the negative pressure gauge according to the practical conditions. The display unit is usually divided into analog type and digital type. The digital display unit is powered by electricity. Thus, the negative pressure gauge having a digital display unit is usually provided with a power-supplying unit therein. For example, a battery is installed in the display unit to supply the necessary electricity, so that the pressure value of the gas flowing through the negative pressure gauge can be displayed on the display unit.
In practice, such a structure of the negative pressure gauge has a problem. Since the display unit is electrically connected to the power-supplying unit, the display unit will display the pressure value of a gas after the battery is installed in the negative pressure gauge. However, the display unit is not provided with a power switch, so that the power-supplying unit will supply power continuously. Even the negative pressure gauge is not in use, the display unit will remain turned on. One solution of this problem is to detach the battery from the negative pressure gauge. Such an action requires more time. Also, when a user intends to use the negative pressure gauge, he/she has to install the battery in the negative pressure gauge again, which makes the user feel inconvenient.
Therefore, in order to overcome the above problems, the present Inventor proposes a reasonable and novel structure based on his delicate researches and expert experiments.